1. Field of the Invention
This invention relates to a construction material, which is large in size, has a panel-like shape and is used as roofing materials and wall materials, and a method of manufacturing the same.
2. Description of the Prior Art
Where heavy weight panels such as precast concrete panels are used as roofing materials on a large span frame or like structure where supports are spaced apart large distances, the panel and support members must have high mechanical strength and the mounting structure is complicated, thus leading to high cost.
On the other hand, in case of light weight panels such as sandwich panels, their manufacture is complicated, leading to high cost. Besides, their durability, rigidity and reliability are inferior.